Peugeot 206 - whirring sound from air conditioning pulley belt?

If the noise goes away with the belt off then you know it is one of the pulleys/idlers that is giving you the problem,don`t know what you mean by over riding the belt,the problem will have to be repaired and the belt refitted,you haven`t said what engine you have here but on some peugeots the crank pulleys give problems

cdc
August 2011